[josm-dev] Clockwise coastline, anti-clockwise water

[Dirk Stöcker]

On Mon, 7 Jul 2008, Martijn van Oosterhout wrote:

>> http://wiki.openstreetmap.org/index.php/Tag:natural=coastline
>> States as anti-clockwise, but regarding the land surrounded by water
>
> Coastline doesn't have to be a single closed way.
>
>> http://wiki.openstreetmap.org/index.php/Tag:natural=water
>> States clockwise, but regarding the water itself and not the land.
>
> And natural=water does.
>
> (Or at least, if the rules have changed then the rendering for mapnik
> will be wrong).
>
> Which, as far as I'm concerned makes the test completely useless for
> natural=water. Does anything actually rely on it? The wiki page says
> its important but doesn't say *why*?

I thought the same. But the check anyway only tests closed ways (there is 
no real useable way to determine this issue for non-closed ways. Think of 
e.g. a U or J shaped way. How will you determine on which side water is 
(You can probably detect minimum distances to 100% land related 
structures and assume the side with these structures is land, but this 
will be a big effort).

To make it a bit more useful, I will an an check, which tests for unclosed 
ways in case of "natural=". That will be helpful.

Ciao
-- 
http://www.dstoecker.eu/ (PGP key available)